Thermopile type infrared sensors shown in the following Patent References 1 to 3 have been conventionally known. In such infrared sensors, a thermocouple is formed by adjacent polysilicon and aluminum, and an infrared ray which is made incident is detected by an infrared detecting part due to this thermocouple.
A thermopile is obtained by arranging the thermocouples in series in a fine area. The thermocouple is a temperature sensor using the principle of the “Seebeck effect” in which a circuit is produced by two kinds of metals and a thermal electromotive force is generated to flow a current when the two junction points thereof are maintained at different temperatures. In the thermocouple, the thermal electromotive force between a temperature measuring junction (hot junction) and a reference junction (cold junction) is measured.
The infrared sensor shown in Patent Reference 1 is an example in which the thermocouple which is composed by p-type and n-type semiconductors is formed on a cantilever. These measure the amount of an infrared ray made incident into the infrared sensor from an electromotive force produced by the temperature difference between the hot junction and cold junction of the thermocouple due to the Seebeck effect, and the high sensitivity of the infrared sensor is realized by arranging a plurality of thermocouples. The infrared sensor provided with an infrared filter is described in Patent Reference 3. An example in which the infrared sensor is formed on an insulated substrate is shown in Patent Reference 3.
[Patent Reference 1]
Japanese Patent Publication No. 2663612
[Patent Reference 2]
Japanese Published Unexamined Patent Application No. Hei-6-249708
[Patent Reference 3]
Japanese Published Unexamined Patent Application No. 2001-174324